Laser power control apparatus and method, an optical disk apparatus and a recording method

Abstract

A laser power control apparatus is for use in an optical disk apparatus for recording information on an optical disk having at least a first layer and a second layer. The laser power control apparatus includes a power control section for controlling a laser element such that a power of a laser beam approaches a control target level; a change detection section for detecting that a recording condition for the optical disk has been changed; and a power adjustment section for adjusting the power of the laser beam for a recording film of the first layer, in accordance with an output from the change detection section. The power adjustment section determines the power of the laser beam for a recording film of the second layer, based on the power of the laser beam which has been adjusted for the recording film of the first layer.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a laser power control apparatus and method for use in an optical disk apparatus for recording information onto an optical disk having a plurality of layers, an optical disk apparatus for recording information onto the optical disk and a recording method for recording information onto the optical disk.[0003]2. Description of the Related Art[0004]As the conventional method for adjusting a power of a laser beam of an optical disk apparatus, a known method includes the steps of adjusting a power of the laser beam according to the temperature and the position along the radial direction of the optical disk, and generating a data table of the power of the laser beam.[0005]For example, the Japanese laid-open publication No. 1-112551 describes a method for determining a power of the laser beam using the data table. This conventional technique will be described with reference to FIG. 12.[0006]FIG....

AI Technical Summary

Benefits of technology

"The patent describes a laser power control apparatus and method for an optical disk apparatus that can adjust the power of the laser beam for recording information on the optical disk. The apparatus includes a power control section that controls the laser element to approach a control target level, a change detection section that detects changes in the recording condition of the optical disk, and a power adjustment section that adjusts the power of the laser beam for the recording film of the first layer based on the control target level and the level of the recording film. The power adjustment section also takes into account the change in the recording film of the second layer, which is determined based on the control target level for the recording film of the first layer and the level of the reference power for the recording film of the second layer. The technical effect of this invention is to improve the accuracy and stability of recording on optical disks, particularly when recording on multiple layers, by adjusting the power of the laser beam for each layer based on the recording conditions of the previous layer."

Problems solved by technology

However, according to the conventional recording method, in the case where the optical disk has a plurality of layers (e.g. two layers) with information recording films, it is impossible to record information onto the recording film of any layer other than the reference layer of the optical disk at the optimal laser power, when the temperature of the environment where the optical disk apparatus is used has been changed.

Specifically, even if a data table for one layer (i.e. the reference layer) is generated and stored in response to the changes in temperature, it is impossible to generate a data table for any layer other than the reference layer.

Taking twice, or more, of the time in making a power adjustment leads to taking twice, or more, of the capacity of the DRAM, which results in increasing the cost of the optical disk apparatus.

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